This invention relates to pressure sensing and more particularly to a pressure sensor having two pressure probes packaged together.
A sensor is a physical device that detects, or senses, a signal or physical condition. Some sensors are particularly adapted to detect chemical compounds. In an ideal situation, the output signal of a sensor is exactly proportional to the value of the property to be measured. An acceptable sensor should be sensitive to the measured property but relatively insensitive to other properties and the sensor should not influence the property to be measured.
Two measures are normally used for evaluating a sensor. A first measure is accuracy which is the degree of conformity to a standard (or true) value of a measured parameter when a sensor is operated under specified conditions. The other important measure is reproducibility which is the closeness of agreement under repeated sensor outputs for the same process variables under the same conditions when approaching from various directions.
In many situations, sensors lose their accuracy due to surrounding environmental factors, Such factors include, for example, temperature and humidity. Both the values of such surrounding environmental factors and the time rate of change of these physical properties contribute to shifting of the sensors' readings from the correct values. Thermal and moisture drifting is a common problem in sensors. Both of these environmental factors can lead to mechanical drawbacks such as adhesive swelling, and/or electrical properties changes.